What is a "sea urchin"?

A sea urchin is a small, spiny marine creature belonging to the echinoderm family. They have a spherical or globular body covered in sharp spines, which serve as a protective mechanism against predators. Sea urchins are found in oceans around the world, inhabiting diverse habitats such as rocky shores, coral reefs, and seagrass beds. They play an important ecological role by grazing on algae and helping to maintain the health of marine ecosystems. Additionally, their unique appearance and delicate movements make them fascinating creatures to observe in underwater environments.